Process for burning off oil spills

ABSTRACT

Process for burning off oil spills, especially on lakes, seas and marginal seas or in the soil, wherein, prior to ignition, the oil slick is sprayed with an incendiary material containing a readily combustible mixture of saturated and/or unsaturated hydrocarbons, preferably containing a readily combustible mixture of saturated hydrocarbons, and the oil slick soaked with this mixture is then ignited, and incendiary composition and priming compound for carrying out the process.

[0001] The present invention relates to a process for burning off oilspills using an incendiary material and preferably a priming compound,and especially for burning off oil spills on lakes, seas or marginalseas or in the soil of coastal areas.

[0002] Oil spills on lakes, seas or marginal seas and in the soil ofcoastal areas usually cause considerable environmental pollution anddamage. Animals and plants immediately suffer substantial damage. Thedamage to zooplankton and phytoplankton can result in the disappearanceof the vital food supply for numerous marine animals in the affectedarea and can endanger the entire local ecosystem. Disasters due to oilspills are very often caused on the oceans by damaged tankers orincidents on drilling rigs, but they can also be caused by illegal tankflushing. Experience has shown that the consequences of oil disasterscannot be satisfactorily remedied using the conventional technologies.

[0003] Transported crude oils sometimes have very differentcompositions. Different deposits produce crude oils of differentcomposition; also, considerable amounts of heavy crude oils emulsifiede.g. with nonylphenol ethoxylate are transported. Individual oilaccidents are therefore seldom comparable to one another. Specific typesof oil contain more volatile and better combustible or misciblecomponents. The outcome of the disaster is also influenced by the airand water temperatures and by the solar irradiation in the region of theaccident. These temperatures influence particularly the evaporation ofthe readily volatile oil components. The less volatile constituents areleft behind as a slick, floating on the water, and over time aredissolved or emulsified in the seawater, are absorbed by plankton oragglomerate into lumps. Parts of the oil slick invade coastal areas andform a sticky mass. If the oil slick sticks to rocky cliffs and reefs,it forms tar-like lumps which take several years to be decomposed bybacteria.

[0004] Mechanical suction is used as a simple method of treatment. Thismethod can be applied on the high seas only in the case of compact oilslicks and on the beach only in the case of a freshly washed-up slick.The use of inflated plastic tubes for containment and suction,optionally in combination with skimmers, is problematic even on aslightly choppy sea because it is normally impossible to prevent atroubled sea from splashing over the oil slick. Applications based onthe use of surfactants are also of dubious value because of the trickydosing problems. This is compounded by the fact that emulsifiers veryoften act as environmental pollutants. After the uptake of small amountsof oil as a result of emulsification, they sink to the bottom of the seaor lake, where they cause damage to the flora and fauna.

[0005] The use of oil-decomposing bacteria requires warmer temperatures,an adequate oxygen supply and a long contact time. The essential aspectof oil removal, however, is that it can be achieved quickly so as tominimize the environmental damage.

[0006] It has now been found that spills of oil, including heavy andviscous oil, in the form of oil slicks on water surfaces such as lakesor seas, or in the soil, can be ignited and extensively burnt off in ashort time if, prior to ignition, the oil slick is sprayed with areadily combustible mixture of saturated and/or unsaturatedhydrocarbons, preferably with a mixture of saturated hydrocarbons (alsoreferred to as “incendiary material” hereafter), and the oil slicksoaked with this mixture is then ignited. Surprisingly, the oil slickcan be completely or almost completely burnt off in this way withoutexhibiting the above-mentioned disadvantages, even if it containsrelatively high proportions of components of low volatility.

[0007] The present invention is defined in the claims. In particular,the present invention relates to a process for burning off oil spillsand especially for burning off oil spills on lakes, seas and marginalseas or in the soil, said process being characterized in that, prior toignition, the oil slick is sprayed with an incendiary materialcontaining a readily combustible mixture of saturated and/or unsaturatedhydrocarbons, preferably containing a readily combustible mixture ofsaturated hydrocarbons, and the oil slick soaked with this mixture isthen ignited.

[0008] As the readily combustible mixture of saturated and/orunsaturated hydrocarbons, it is preferred to use hydrocarbons havingfrom 4 to 12, preferably from 5 to 10 and particularly preferably 5, 6,7 or 8 carbon atoms, or a mixture thereof. The boiling point of themixture ranges preferably from 35° C. to 230° C. and particularlypreferably from 40° C. to 200° C. These hydrocarbons can be linear,branched or cyclic.

[0009] It is preferred to use a mixture of saturated hydrocarbons of theformula C_(n)H_(2n+2), in which n is an integer from 5 to 8, preferably5, 6 or 7 and particularly preferably 5 or 6. The boiling point of themixture ranges preferably from 35° C. to 110° C. and particularlypreferably from 40° C. to 130° C.

[0010] In addition to the hydrocarbons, the incendiary materialpreferably contains at least one additive which improves the Theologicalproperties or the flowability of the oil slick, acts as a solubilizerand/or promotes combustion, or a mixture of such additives,deflagrations simultaneously being avoided by the delaying action of theadditive(s).

[0011] Examples of additives which improve the rheological propertiesare di(C₂-C₁₂)alkyl phthalates, preferably diethyl phthalate, dibutylphthalate, dioctyl phthalate, di(2-ethylbutyl) phthalate or diamylphthalate.

[0012] Examples of additives which promote combustion are cyclohexanol(hexalin) or toluene.

[0013] The incendiary material can contain up to 20% by weight,preferably about 5% by weight to 10% by weight, of additives.

[0014] The amount of incendiary material added to a particular oil slickdepends on the composition or combustibility of the oil slick. Thisoptimum amount to be added can easily be determined experimentally ineach case by those skilled in the art.

[0015] Accordingly, the present invention further relates to an agent oran incendiary composition for burning off oil spills and especially forburning off oil spills on lakes, seas or marginal seas or in the soil,said agent being characterized in that it contains a readily combustiblemixture of saturated and/or unsaturated hydrocarbons, preferably areadily combustible mixture of saturated hydrocarbons, and additiveswhich improve the rheological properties or the flowability of the oilslick, act as solubilizers and/or promote combustion, as described aboveand in the following text.

[0016] The burn-off of poorly ignitable and poorly combustible oilslicks, for example a bituminous slick, can be further improved by theaddition of a gas generator, for example calcium carbide. In contactwith water, calcium carbide decomposes to form readily ignitableacetylene gas.

[0017] The oil slick sprayed with the incendiary material is preferablyignited by means of a priming compound. The priming compound preferablyconsists of the above-defined combustible mixture of saturated and/orunsaturated hydrocarbons (incendiary material), said incendiary materialbeing sealed in plastic packaging, preferably in polypropylene bags, inamounts of 0.5 kg to 2.0 kg. Fixed to the packaging is an igniter cordconnected to a pull fuse by means of a match cord. The igniter cord canbe stuck or tied to the packaging. To prevent water or moisture fromentering said combination and damaging it, the entire priming compoundis preferably wrapped in or protected by a second bag, for example madeof polyethylene. The preferred polypropylene bags are resistant to thehydrocarbons and any additives present and are not attacked by them.Pull fuses, their construction and possible compositions are known perse.

[0018] Accordingly, the present invention relates to a priming compoundconsisting of a combustible mixture of saturated and/or unsaturatedhydrocarbons as defined above, said incendiary material being sealed inplastic packaging, preferably in polypropylene bags, in amounts of 0.5kg to 2.0 kg, and an igniter cord, connected to a pull fuse by means ofa match cord, being fixed to said packaging.

[0019] This priming compound is very easy to handle. First the pull fuseis operated, after which the appropriately timed match cord begins toburn and transfers the fire to the readily ignitable igniter cord,thereby triggering effective combustion involving the entire primingcompound.

[0020] Crude oil compositions from different sources are very different,especially as regards the content of naphtha (b.p. 40-200° C.),petroleum (b.p. 200-275° C.), gas oil (b.p. 275-360° C.), heavy oil(b.p. 360-500° C.) and residue. Thus the boiling profile and thecomposition remaining as the oil slick are also different. Crude oilcompositions from different sources, for example

Pennsylvania Brandf.

,

California Paloma

, Texas Sulfur Bluff

or

Trinidad

crude, are known per se.

[0021] To successfully burn off an oil slick originating from an oilpest, the procedure according to the invention is first to spray theincendiary material over the oil slick, for example with a pressurepump, or release the incendiary material on to the slick from anaeroplane, and allow the incendiary material to make contact with theoil slick. This contact time depends primarily on the particular outsidetemperature and water temperature. The priming compound is then thrownon to the oil slick to trigger the burn-off. If the oil layer iscoherent, quiet combustion can be expected. The process according to theinvention optimizes the ignition behaviour and achieves an even burn-offof the oil slick. Deflagrations or explosive phases are avoided. Expertapplication of the process eliminates up to 95% of the oil slick byburn-off. The following Examples illustrate the invention.

EXAMPLE 1

[0022] (Incendiary Composition)

[0023] The following components are combined to form an incendiarymixture which can be used according to the invention. Incendiarycomponent: Parts by weight: White spirit* containing 40% of alkanes 30.0Hexane (technical grade) 15.0 Cyclohexane (technical grade) 12.0 Pentane(normal pentane) 10.0 Heptane (technical grade) 15.0 Decalin(decahydronaphthalene, technical grade) 10.0 Dimethylformamide 5.0Dibutyl phthalate 3.0 Total end product 100.0

EXAMPLE 2

[0024] (Priming Composition) Priming component: Parts by weight: Specialboiling point spirit (b.p. 80° C.-110° C.) 88.0 Highly disperse silicicacid 6.0 Sodium stearate (finely powdered) 1.0 Zinc oleate 5.0 Total endproduct 100.0

EXAMPLE 3

[0025] (Gas Generator Composition)

[0026] If a bituminous slick is involved, a gas generator is preferablyalso used in combination with the priming compound so that the burn-offleaves as little residue as possible. Gas generator: Parts by weight:Calcium carbide (calcium acetylide 95.0 (technical grade), in pieces(5-10 mm) Highly disperse silicic acid (Aerosil type) 5.0 Total endproduct (in dust form) 100.0

1. Process for burning off oil spills, especially on lakes, seas andmarginal seas or in the soil, characterized in that, prior to ignition,the oil slick is sprayed with an incendiary material containing areadily combustible mixture of saturated and/or unsaturatedhydrocarbons, preferably containing a readily combustible mixture ofsaturated hydrocarbons, and the oil slick soaked with this mixture isthen ignited.
 2. Process according to claim 1, characterized in that amixture of saturated and/or unsaturated hydrocarbons having from 4 to12, preferably from 5 to 10 and particularly preferably 5, 6, 7 or 8carbon atoms, or a mixture thereof, is used as the incendiary material.3. Process according to claim 2, characterized in that the mixture has aboiling point in the range from 35° C. to 230° C., preferably in therange from 40° C. to 200° C.
 4. Process according to claim 2,characterized in that a mixture of saturated hydrocarbons of the formulaC_(n)H_(2n+2), in which n is an integer from 5 to 8, preferably 5, 6 or7 and particularly preferably 5 or 6, is used as the incendiarymaterial.
 5. Process according to claim 4, characterized in that themixture has a boiling point in the range from 35° C. to 110° C.,preferably in the range from 40° C. to 130° C.
 6. Process according toone of claims 1-5, characterized in that the incendiary materialcontains at least one additive which improves the rheological propertiesof the oil slick, acts as a solubilizer and/or promotes combustion, or amixture of such additives.
 7. Process according to claim 6,characterized in that the additive is a di(C₂-C₁₂)alkyl phthalate,preferably diethyl phthalate, dibutyl phthalate, dioctyl phthalate,di(2-ethylbutyl) phthalate or diamyl phthalate.
 8. Process according toclaim 6, characterized in that the additive contains cyclohexanol(hexalin) or toluene.
 9. Process according to one of claims 1-8,characterized in that the incendiary material contains up to 20% byweight, preferably 5% by weight to 10% by weight, of additives. 10.Process according to one of claims 1-9, characterized in that a gasgenerator, preferably calcium carbide, is also added to the oil slick.11. Process according to one of claims 1-10, characterized in that theoil slick sprayed with the incendiary material is ignited by means of apriming compound.
 12. Incendiary composition for burning off oil spills,characterized in that it contains a readily combustible mixture ofsaturated and/or unsaturated hydrocarbons according to claims 1-5 andadditives according to claims 6-9.
 13. Incendiary composition accordingto claim 12, characterized in that a gas generator, preferably calciumcarbide, is also added.
 14. Priming compound for use in the processaccording to one of claims 1-11, consisting of a combustible mixture ofsaturated and/or unsaturated hydrocarbons according to one of claims1-5, said incendiary material being sealed in plastic packaging,preferably in polypropylene bags, in amounts of 0.5 kg to 2.0 kg, and anigniter cord, connected to a pull fuse by means of a match cord, beingfixed to said packaging.